| 摘要 |
The present invention relates to a sub-carrier filter and demodulator for a wireless communication receiver, comprising two mixers (10) each connected to receive a same sub-carrier signal (V x ) and respectively driven by two quadrature signals produced by a local oscillator (11) and to apply down-converted signals to respective low-pass filters before they are fed into a digital FSK demodulator circuit, wherein said mixers (10) are driven by triangular wave signals (LOl,LOQ) and comprise:
- a first differential pair of transistors (24-25) having bipolar characteristics, for converting said sub-carrier signal (V x ) into two currents (I 1 ,l 2 ), and
- second and third pairs of transistors (16-18,17-19) having bipolar characteristics, for respectively multiplying said currents (I 1 ,l 2 ) with said triangular wave signals (LOl,LOQ) and applying them to said low-pass filters (12).
Application to UWBFM for reducing harmonics in mixers for downconversion.
Mixers are implementable as Gilbert cells.
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